US3725849A

US3725849A - Plug in antenna, antenna base and test probe system

Info

Publication number: US3725849A
Application number: US00083552A
Authority: US
Inventors: E Becke
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1970-10-23
Filing date: 1970-10-23
Publication date: 1973-04-03
Anticipated expiration: 1990-04-03

Abstract

An antenna mounting system, including a base plate having a rear coaxial connector to which a coaxial cable is permanently attached. The base plate is permanently attached to the exterior of the mounting surface with the coaxial connector extending inwardly thru a hole in the mounting surface. An antenna mounting plate or a test probe fits onto the base plate. The antenna or test probe is secured to the base plate by bolts, thereby allowing for the rapid removal of the antenna and replacement thereof by the test probe.

Description

A United States Patent [191 Becke- [111 3,725,849 [451 Apr. 3, 1973 [54] PLUG IN ANTENNA, ANTENNA BASE ANDTEST PROBE SYSTEM [75] Inventor: Edward G. Becke, Camp Springs,

[73] Assignee: The United States of America as represented by the Secretary of the Navy [22] Filed: Oct. 23, 1970 [21] Appl. No.: 83,552

[52] US. Cl ..339/92 R, 339/126 .1, 339/117 R [51] Int. Cl. ..H0lr 17/06 [58] Field of Search ..l74/75 C, 88 C, 89,152 A,

174/153 A; 339/60 C, 89 C, 90 C, 91 P, 92, 94 C, 126 J, 132, 177, 64, 121; 343/714, 718, 789, 845, 872, 873, 888, 906, 793, 830

[56] References Cited UNITED STATES PATENTS 3,566,334 a 2 1971 Ziegler ..339 177 R 2,332,529 10/1943 Reppert ..339/177 R 3,047,828 7/1962 Gregson et al.... .....339/177 R 2,627,026 1/1953 Kandoian et al. ..343/793 Primary Examiner-Marvin A. Champion Assistant Examiner-Lawrence J. Straab Attorney-R. S. Sciascia, Arthur L. Branning and James G. Murray [57] ABSTRACT An antenna mounting system, including a base plate having a rear coaxial connector to which a coaxial cable is permanently attached. The base plate is permanently attached to the exterior of the mounting surface with the coaxial connector extending inwardly thru a hole in the mounting surface. An antenna I mounting plate or a test probe fits onto the base plate.

The antenna or test probe is secured to the base plate by bolts, therebyallowing forthe rapid removal of the antenna and replacement thereof by the test probe.

6 Claims, 6 Drawing Figures BASE PLATE PATENTEUAPRS 197; 3,725,849

SHEET 2 OF 2 FIG: 6

FIG. 5

BASE

PLATE PLUG IN ANTENNA, ANTENNA BASE AND TEST PROBE SYSTEM STATEMENT OF GOVERNMENT INTEREST BACKGROUND OF THE INVENTION This invention relates to apparatus for mounting antennas on exterior surfaces, and more particularly to an antenna mounting assembly for mounting a multitude of antennas in anarray on the exterior surface of moving vehicles.

In the antenna art, designers often use a multitude of small antennas in an array to replace a single large antenna. This improves performance but introduces other problems which are not encountered to a significant degree using single antenna systems. One of the problems that has arisen is that of making and testing a multitude of coaxial cables connecting from the antennas to the related electronic equipment.

' As is well known, the coaxial cable used for electrically connecting an antenna to its related receiving and/or transmitting equipment includes a central conductor surrounded by electrical insulation which in turn is surrounded by some form of metal sheath. In making a coaxial cable connection, it is necessary to make a connection to the central conductor and also to' the metallic sheath. The metallic sheath is frequently formed of a interwoven mesh of fine metal wires which can withstand only a very small amount of mechanical abuse such as frequently occurs during the manipulation necessary in making repeated coaxial cable connections. It is not uncommon, therefore, for the electrical connections between the ground sheath of the coaxial cable and the coaxial cable connector to become damaged or actually separate after a certain number of connect-disconnect cycles. This necessitates either a predetermined schedule of coaxial cable connector replacements, or a large and well trained trouble shooting staff. Both alternatives are undesirable from the standpoint of cost and technical personnel staff size necessary.

Other prior art systems employ coupling devices which allow for the testing of an rf system without disassembly of the rf system by coupling in the test equipment. These coupling techniques are rather inefficient lost and valuable man hours expended. This burden,

however, was not serious when only a few antennas were involved. Now, however, when a multitude of antennas in an array are involved, the burden is multiplied many-fold and has now reached critical proportions.

Yet another problem involved in the existing procedures is the necessity to provide several extra feet of coaxial cable connected to the antenna. When the antenna is unbolted from .the exterior surface of the vehicle and pulled away from the vehicle there must be several extra feet of coaxial cable to give the technician enough working room to make the cable disconnection from the antenna. This extra loose cable causes the usual rf attenuation in the signal and also raises the possibility of fouling and mechanical damage to the several lengths of coaxial cable stored behind the antenna mounting area.

One of the reasons for the notorious unreliability of the prior art coaxial cable connection system is that it is almost universally true that the mechanical connection at less than wave guide frequencies, as they cause fairly substantial rf losses; and the repeatability of various tests such as sensitivity, power and impedance is not satisfactory. Therefore such coupling devices are not desirable in a system where periodic precise and consistent measurements are needed.

Another problem that has been with the antenna art betweenthe coaxial connectors is also the electrical ground connection between the coaxial cables. This situation makes it virtually inevitablethat the electrical conductance at the ground connection will deteriorate because of corrosion, dirt, grease and/or other foreign matter which commonly accumulates at mechanical connecting means such as the usual threaded connection. In addition, since the ground connection is also the mechanical connection, any vibration or other mechanical stress is necessarily shared by the electrical connection, and high frequency intermittent interruptions in the ground connection occasionally result. Also,.when mechanical damage occurs to the connector mechanism, it necessarily requires the replacement of .the entire connector assembly and eventually requires the replacement of the extra working length of coaxial cable because each replacement of the connector consumes several inches of cable and eventually the working length becomes too short.

Another serious problem arising because of prior art coaxial cable connector design occurs when the antenna is struck as the vehicle passes close to an obstruction I such as another vehicle, debris, or ice in the water. When this occurs, the antenna and. its mounting plate are usually torn from the vehicle together with the piece of vehicle skin to which they are mounted, leaving a gaping hole in the vehicle. The coaxial cable is carried away with the antenna and delivers a severe jerk to the connection within the vehicle or usually both. The resulting damage is extremely severe. The vehicle skin must be repaired, a new antenna mounted to the skin, and the electrical equipment within the vehicle repaired.

The art has thus long been in search of an antenna mounting system which provides a quick and easy coaxial antenna connection with a positive and reliable connection, a highly secure mechanical connection, a provision allowing the antennato be sheared from the vehicle without damage to the vehicle or the related electronic equipment, and a design which provides sufficient ruggedness that the connection and disconnection cycle may be made as often as necessary throughout the life of the antenna without fear of damaging a delicate electrical connection.

SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide an antenna mounting system which makes possible fast and easy connection and disconnection of the antenna from the vehicle.

Another object of the present invention is to provide anantenna mounting system with highly reliable impedance match in the electrical connection.

Yet another object of this invention is to provide an antenna mounting system with a test probe for making fast and reliable tests of the antennarelated electronic equipment.

A still further object of this invention is to provide an antenna mounting system having a break-away feature which allows the antenna to be carried away from the vehicle on impact with a foreign body without damage to the vehicle. I

Still another object of this invention is to provide an antenna mounting system for an antenna on a vehicle which gives good electrical contact between the antenna and the coaxial cable independent of the mechanical connection of antenna and the coaxial cable connector.

The time savings involved can be very great where a series of tests must be made repeatedly with consistent accuracy. If for instance there is a saving of 1 minute per antenna change and test in a system having 60 antennas this amounts to an hour saved. There are systems in which one complete tests using the invention could amount' to a one man week saved thus greatly reducing the total test time required. The repeatability and accuracy of these tests is very important where system reliability is a must.

Briefly, in accordance with one embodiment of this invention, these and other objects are attained by providing a base plate which may be permanently secured to the vehicle, and an antenna mounting plate which may be secured to the base plate by means of shear bOltSuA coaxial boss extends outward from the face of the base plate andinto a complementary sized cavity in the antenna mounting plate. In the center of the coaxial boss there is a female coaxial connector which mates with the male coaxial connector located in the center of the cavity in the antenna mounting plate. The height of the boss is approximately equal to the depth of the cavity while depth of the female coaxial connector in the boss is slightly less than the height of the male coaxial connector in the cavity so that when the antenna mounting plate is bolted to the base plate the central portion of the antenna mounting plate flexes outward slightly like a diaphragm causing a constant pressure to be exerted between outer conductors of the male and female coaxial connectors thereby maintaining a positive connection and a proper impedance match. A coaxial cable may be permanently secured to the inside face of the base plate and once secured need never be touched again. When struck by foreign objects, the antenna bolts will shear and the entire antenna and antenna mounting plate will be carried away leaving the base plate 'and coaxial cable connected thereto intact.

A second embodiment of the invention is provided wherein the coaxial boss extends outward from the antenna. mounting plate and is complementary mated with the cavity in the base plate. The male coaxial connector, also in this embodiment, extends outward to a slightly greater extent than the depth of the mating female connector thereby maintaining a positive con- DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and its many attendant advantages will develop as the same becomes better understood'by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FlG. -l is a section elevation of the central portion of a base plate secured to the exterior skin of a vehicle;

FIG. 2 is a sectional elevation of the central section of an antenna mounting plate; and

FIG. 3 is a sectional elevation of a test probe mounting plate;

FIGS. 4, 5 and 6 are similar to those of FIGS. 1, 2 and 3 respectively except that the coaxial boss extends from the antenna and test probe mounting plates while the mating cavity is formed in the base plate.

' Referring now to the drawings and more particularly to F IG. 1, a base plate 10 is'shown having a planar section 12 through which are formed on the outer periphery'thereof a series of smooth bored holes 14 which receive means such as bolts 15 by which the base plate may be permanently secured-to the skin of the vehicle to which the antenna is to be mounted. A series of threaded holes 16 spaced radially from holes 14 are formed in planar portion 12 for a purpose to be described later. I

A coaxial boss 18 is integrally formed on planar portion 12 and extends outwardly therefrom a distance h. A central bore 20 extends axially through coaxial boss 18 and planar portion 12 and has threads formed on the interior surface thereof. A female coaxial connector 22 is threadedly received within bore 20 and includes a plug 24 of insulating material such as Teflon in which is axially mounted an electrical conductor 26 extending completely through plug 24 and communicating with the forward and rearward surfaces thereof. The conductor 26 is drilled out on its forward and rearward ends to provide receptacles for the male coaxial con ductor. Female coaxial connector 22 has formed on its rearward end a threaded connection 27 to which may be attached a conventional coaxial cable connector. Each of the female ends of female coaxial connector 22 are of a depth 1 foot to a bearing surface 29.

Base plate 10 ispermanently bolted to a desired surface or to the exterior skin of a vehicle such as a tank, a trunk, or a submarine with the threaded connection 27 extendingthrough an aperture in the skin of the vehicle. A coaxial cable (not shown) can be connected to the connector 27 and the entire aperture and connection sealed with an additional application of epoxy adhesive (not shown). This procedure wouldseal the antenna connection to the vehicle and isolate the coaxial cable connection from all further mechanical vibration. The mechanical and electrical connection of the base plate to the vehicle is thus well insulated from normal vibration, moisture and other detrimental influences which commonly cause deterioration of electrical con tact.

Looking now at FIG. 2 an antenna mounting plate 30 is shown having a planar portion 32 which may be of the same lateral dimensions as the planar portion 12 of base plate 10. A series of holes 34 is formed through planar portion 32 in alignment with holes 16 formed in planar portion 12 of base plate for the purpose of receiving fasteners such as bolts by which mounting plate 30 may be secured to base plate 10. A second series of holes, not shown, may be formed radially farther out from the axis of antenna mounting plate 30 than holes 34 to align with a second set of threaded holes, not shown, in base plate 10 for the purpose of adding greater mechanical security to the attachment of mounting plate 30 to base plate 10.

A cylindrical boss 36 is formed on the outside of mounting-plate 30 and extends outwardly therefrom. A cylindrical cavity 38 is formed on the inside of mounting plate 30 extending into cylindrical boss 36 and is of dimensions generally complementary to coaxial boss 18. An axial bore 40 is formed through boss 36 communicating between the center of the inside face of cavity 38 and the outside face of boss 36. An annular shoulder 42 is formed on the outside face of boss 36 surrounding bore 40. A tubular sleeve 44 fits snugly within bore 40 and has an annular rim 46 of identical lateral dimensions as annular shoulder 42" to enable rim 46 to lie in shoulder 42. An antenna base 48 having an axial tubular standard 50 extending outwardly therefrom is secured to the outside face of cylindrical boss 36 by fasteners such as bolts 52. Insulating material 54 such as Teflon is received in tubular sleeve 44 and extends up into tubular standard 50 and with a central conductor 56 forms a coaxial cable leading to the antenna (not shown). The tubular sleeve 44 and insulating material 54 of male coaxial connector 58 extend outward from the rear surface of the cavity 38 to a height 1 which is slightlyv greater than the depth 1 foot of the female coaxial connector 22. A housing (not shown) made of a strong, light material such as fiberglass surrounds the antenna and is secured with a water-tight seal to the outside periphery of planar portion 32 to protect the antenna and coaxial cable connection from the ambient environment.

Referring now to FIG. 3, a test probe mounting plate 60 is shown having a planar portion 62 and a central cylindrical boss 63. Mounting plate 60, cavity 64 and male coaxial connector 78 are identical to mounting plate 30 except that planar portion 62 has attached thereto a plurality of fastener assemblies 65, only one of which is shown. Each fastener 65 has a screw 66 permanently attached to plate 60 by mounting ferrule 68 and biased outwardly by spring 70. Panel fastener assemblies 65 enable the test probe mounting plate 60 to be quickly attached to plate 10 and disconnected therefrom when it is desired to make a test of the antenna related electrical equipment. A female coaxial connector 72 is fastened by bolts 79 to the outside face of cylindrical boss 63 and provides a threaded connection 74 and a berylium copper receptacle 76 to receive a conventional threaded coaxial cable connector. Thus when it is desired to make tests of the antenna related electrical equipment, the test probe is mounted on the base plate by securing screws 66 in threaded holes 16 in base plate 10 and signals from a signal generator (not shown) are supplied through the coaxial cable attached to connector 72 and the tests are made. When the tests are completed, screws 66'are withdrawn from holes 16 and the test probe is removed from base plate 10. It is apparent therefore that no manipulations of the internal coaxial cable connectors need be made.

It is a further envisioned that the test probe mounting plate could be attached by the securing screws 66 in a standardized fashion, that is the screws 66 could use a separate set of standard securing holes (not shown) other than these of the antenna mounting plate 30. Thus the antenna mounting plate 30 and the base plate 10 could be made larger for different types of antennas while the coaxial boss 18, mating cavities 38 and 64, and the test probe mounting plate holes could be standardized thereby allowing one test probe to be used to test many different types of antenna systems having various sized base plates. It is obvious that the same standardization could apply to the base plate 80, antenna mounting plate 100 and test probe 120 of FIGS. 4, 5 and 6, respectively.

Further is should be noted that this mounting system could be used to mount most any type of antenna such as, cone, dipole, stub, monopole, whip antennas and including all types of antennas up to wave guide frequen cies that can be fed by coaxial cable.

Thus, one of the principal advantages achieved by the use of this invention is in the elimination of repeated manipulation of conventional coaxial cable connectors. Once the initial connections of the coaxial cables to the base plate and the test probe are made, they need never be disconnected again. Thereafter, the coaxial connection is made by female coaxial connector 22 with male coaxial connectors 58 and 78. Excellent electrical ground contact is achieved by making the depth 1 foot of the female coaxial connector slightly shallower than the height 1 of the male coaxial connectors 58 and 78 so that when mounting

plates

60 or 30 are secured to the base plate 10 the central portion of the mounting plates flex outward slightly in the manner of a diaphragm to cause the outer conductors of male coaxial connectors 58 and 78 to exert a constant pressure against bearing surface 29. This constant pressure assures excellent electrical ground contact which is maintained despite vibration of the mounting plate. As shown in FIGS. 1 and '3, the dimension 1 foot should be slightly less than dimension 1, and an analogous dimension in FIG. 2.

Referring to FIGS. 4, 5 and 6 which are similar to FIGS. 1, 2 and 3 respectively except that the locations of the coaxial boss and the mating cavity are reversed. F IG. 4, shows a sectional elevation of the base plate 80 with a cylindrical boss extend thru the mounting surface on skin 82. The exterior or outer portion of the base plate contains the cavity 92 which is to mate with the

coaxial boss

104 or 124 of the antenna mounting plate or test probe 120, respectively. On the interior of the skin there is located a coaxial connector 84 which once connected need not be disconnected for replacement of the antenna or to test the antenna system. Located in the cavity is a tubular sleeve 86 which supports the insulating Teflon plug 88 and acts as an exterior conductor for the coaxial feed when the antenna or test probe is in place, while the conductor 90 serves as the inner coaxial feed conductor thus forming a male coaxial connector 91. As shown tubular sleeve 86 extend to a height 1 from the rear surface of the cavity 92.

In FIG. 5, the antenna mount 100, which mates with the base plate 80, includes a coaxial boss 104 which extends into the cavity 92.

Female coaxial connector has a bearing surface 106 recessed to a depth 1 foot and a center conductor 114 surrounded by insulation 110 which extends up thru tubular standard 108 which is mounted on boss 102. An antenna (not shown) connects to the, coaxial feed formed by tubular standard 108, insulation 110 and center conductor 1 14.

Test probe 120 as shown in FIG. 6 is quite similar to the antenna mounting plate 100 except for the female coaxial connector 126 to which is connected a test cable (not shown). The remaining components perform the same function as those shown in F IG. 5. Coaxial boss 124 contains female connector 132 which has a bearing surface 128 recessed to a depth 1 foot, a center conductor 134 and insulator 130.

As in the previously discussed FIGS. 1, 2 and 3 the female coaxial connectors 112 and 113 are slightly shallower than the height of the male coaxial connector 91 to provide the desired diaphragming action and maintain excellent electrical ground contact.

Since the ground contact is mechanically independent of the means for securing the mounting plate to the base plate, mechanical damage to the securing.

means does not harm the electrical contact structure at all. It is therefore possible to coat the contact structure with material such as gold which enhances the electrical contact without the need for protecting the contact enhancing material frommechanical damage by the securing means. Thus if the mechanical securing means and the electrical ground contact means were the same structure, such as the conventional threaded contacts, coating the threads with gold would be impractical because the gold would soon be abraded away by repeated connect and disconnect cycles of the threaded contact. This invention separates the mechanical connection from the electrical connection so that the electrical connection, mechanically isolated from the mechanical connection, is protected from injury commonly sustained by the mechanical securing means. The mechanical connection is further separated in that the mounting bolts form the securing portion while the alignment and mechanical strength of the electrical connection is supported by the mating of the coaxial boss with the cavity forming an mechanical malefemale connection that is independent of the electrical male-female coaxial connection.

Naturally, numerous modifications of the above described best mode are possible. It is therefore to be understood that the essential inventive concept of the invention as defined in the appended claims may be embodied in structure different from that specifically described herein. Of course appropriate sealing methods may be used for the desired purpose to which the mounting system is put.

What is claimed and desired to be secured by letters patent of the United States is:

1. An antenna mounting system, comprising:

a first mountingplate; a second moun mg plate;

mechanical means for mechanically connecting said first mounting plate to said second mounting plate; electrical means for making an electrical connection between said first mounting plate and said second mounting plate; and said mechanical connecting means being mechanically isolated from said electrical means; said electrical means comprising a cylindrical boss extending outward from and being a rigidly attached, integral extension of said second mounting plate having a female coaxial connector centrally located therein and being mated with a male coaxial connector centrally'located ina cavity in said first mounting plate thereby forming an electrical coaxial connection between said first mounting plate and said second mounting plate. 7 2. An antenna mounting system according to claim 1 wherein said firstmounting plate is an antenna mounting plate; and said second mounting plate is a base plate.

3. An antenna mounting system according to claim 1 wherein said first mounting plate is a base plate; and

said second mounting plate is an antenna mounting plate. a a

4. An antenna mounting system according to claim 1 wherein said first mounting plate is a test probe plate; and said second mounting plate is a base plate.

5. An antenna mounting system according to claim 1 wherein said first mounting plate is a base plate; and said second. mounting plate is a test probe plate.

6. An antenna mounting system according to claim 1 wherein said male coaxial connector extends outwardly a sightly greater distance than the. depth of said female coaxial connector.

Claims

1. An antenna mounting system, comprising: a first mounting plate; a second mounting plate; mechanical means for mechanically connecting said first mounting plate to said second mounting plate; electrical means for making an electrical connection between said first mounting plate and said second mounting plate; and said mechanical connecting means being mechanically isolated from said electrical means; said electrical means comprising a cylindrical boss extending outward from and being a rigidly attached, integral extension of said second mounting plate having a female coaxial connector centrally located therein and being mated with a male coaxial connector centrally located in a cavity in said first mounting plate thereby forming an electrical coaxial connection between said first mounting plate and said second mounting plate.

2. An antenna mounting system according to claim 1 wherein said first mounting plate is an antenna mounting plate; and said second mounting plate is a base plate.

3. An antenna mounting system according to claim 1 wherein said first mounting plate is a base plate; and said second mounting plate is an antenna mounting plate.

5. An antenna mounting system according to claim 1 wherein said first mounting plate is a base plate; and said second mounting plate is a test probe plate.

6. An antenna mounting system according to claim 1 wherein said male coaxial connector extends outwardly a sightly greater distance than the depth of said female coaxial connector.